Photoelectric conversion apparatus and image pickup system

ABSTRACT

A photoelectric conversion apparatus includes a photoelectric conversion unit having a light incident surface and including: a first electrode; a second electrode disposed further toward the light incident surface; and a photoelectric conversion layer disposed between the first and second electrodes. The photoelectric conversion apparatus includes a member in contact with the photoelectric conversion layer and constituting a light guide together with the layer. An area of a first surface parallel to the light incident surface at a portion of the photoelectric conversion layer surrounded by the member is smaller than an area of a second surface disposed between the first surface and the second electrode at a portion of the photoelectric conversion layer surrounded by the member, and an area of orthogonal projection to the light incident surface of the first electrode is smaller than an area of orthogonal projection to the light incident surface of the second surface.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/811,670, filed on Jul. 28, 2015, which claims priority fromJapanese Patent Application No. 2014-156786 filed Jul. 31, 2014, whichis hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a photoelectric conversion apparatusand an image pickup system using a photoelectric conversion apparatus.

Description of the Related Art

A photoelectric conversion apparatus using a photoelectric conversionlayer provided on a semiconductor substrate has been proposed. JapanesePatent Laid-Open No. 2012-064822 describes a photoelectric conversionapparatus that includes a photoelectric conversion layer provided foreach pixel and disposed between an upper electrode and a lowerelectrode. The upper electrode and the photoelectric conversion layerdescribed in Japanese Patent Laid-Open No. 2012-064822 extend to reach apixel boundary portion and, therefore, a photoelectric convertible areahas a high area occupancy in a single pixel (i.e., an aperture ratio ishigh). The lower electrode described in Japanese Patent Laid-Open No.2012-064822 is provided to extend from the pixel boundary portion to thepixel boundary portion in the same manner as the upper electrode and thephotoelectric conversion layer. Since the lower electrode constitutes apart of capacitance of the photoelectric conversion layer, thecapacitance of the photoelectric conversion layer varies in accordancewith the shape of the lower electrode. In the photoelectric conversionapparatus, in the case where capacitance for accumulation of charge inthe photoelectric conversion layer is increased, noise (kTC noise)superimposed on photoelectrically converted signals may increase. Thepresent invention reduces noise in the signals generated in thephotoelectric conversion layer while maintaining the aperture ratio ofthe photoelectric conversion layer.

SUMMARY OF THE INVENTION

In an aspect of the present invention, a photoelectric conversionapparatus including a photoelectric conversion unit provided with alight incident surface, the photoelectric conversion unit including: afirst electrode; a second electrode disposed further toward a lightincident surface than the first electrode; and a photoelectricconversion layer disposed between the first electrode and the secondelectrode. The photoelectric conversion apparatus includes a member thatis in contact with the photoelectric conversion layer and thatconstitutes a light guide together with the photoelectric conversionlayer, an area of a first surface that is parallel to the light incidentsurface and is located in the photoelectric conversion layer surroundedby the member is smaller than an area of a second surface disposedbetween the first surface and the second electrode and is located in thephotoelectric conversion layer surrounded by the member, and an area oforthogonal projection to the light incident surface of the firstelectrode is smaller than an area of orthogonal projection to the lightincident surface of the second surface.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view illustrating a first embodiment.

FIG. 2 is a schematic sectional view illustrating the first embodiment.

FIG. 3 is a schematic sectional view illustrating a second embodiment.

FIG. 4 is a schematic sectional view illustrating a third embodiment.

FIGS. 5A and 5B are schematic sectional views illustrating a fourthembodiment.

FIG. 6 is a schematic sectional view illustrating a fifth embodiment.

FIGS. 7A and 7B are schematic plan views illustrating the firstembodiment.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

A first embodiment is described with reference to FIGS. 1 and 2. Commonor known techniques are applied to the portions that are not illustratedor described in the specification. For the ease of description, an areaof each configuration may be described using a width in cross section ofeach configuration.

FIG. 1 illustrates a schematic plan view of a photoelectric conversionapparatus 100. The photoelectric conversion apparatus 100 includes aregion 101 including a light receiving region 10, and a region 102including a light-shielded region 20 and a peripheral circuit region 30.The region 102 is provided outside the region 101. A plurality of pixelsare arranged in two dimensional arrays in the light receiving region 10and in the light-shielded region 20. Each of the pixels includes atleast one photoelectric conversion unit and a readout circuit forreading signals produced in the photoelectric conversion unit. Thereadout circuit includes, for example, a transfer transistorelectrically connected to the photoelectric conversion unit, anamplifying transistor having a gate electrode electrically connected tothe photoelectric conversion unit, and a reset transistor for resettingthe photoelectric conversion unit. The peripheral circuit region 30 is aregion in which peripheral circuits that control an operation of thelight receiving region 10 and process the signals read from the lightreceiving region 10 are disposed. The peripheral circuit region 30includes, for example, processing circuits, such as an amplifiercircuit, a horizontal scanning circuit, and a vertical scanning circuit.The light-shielded region 20 and the peripheral circuit region 30 arecovered with a light-shielding film when seen from a direction verticalto a surface of a semiconductor substrate. The light receiving region 10is a region where a light-shielding film is not provided or alight-shielding film opened at pixels is provided when seen from adirection vertical to a surface of a semiconductor substrate. Thus,light reaches the photoelectric conversion unit in the light receivingregion 10. At least some of the pixels arranged in the light-shieldedregion 20 are optical black pixels (OPB pixels), and signals obtained bythe OPB pixels are used as the black reference signal. That is, theregions 101 and 102 can be provided. The region 101 includes the lightreceiving region 10, and the region 102 includes the light-shieldedregion 20 and the peripheral circuit region 30. The region 102 isprovided outside the region 101.

FIG. 2 is a cross sectional view along line II, III, IV-II, III, IV inthe schematic plan view of FIG. 1. The line II, III, IV-II, III, IVextends across the regions 101 and 102. In the region 101, a pluralityof photoelectric conversion units 218 are provided on a semiconductorsubstrate (hereafter, referred also to as a substrate) 201. Here, twophotoelectric conversion units 218 are illustrated. Two photoelectricconversion units 218 are arranged in a direction parallel to a surface202 of the substrate 201. Here, a direction vertical to the surface 202and away from the surface 202 is defined as an upper direction, and adirection vertical to the surface 202 and approaching to the inside ofthe substrate 201 is defined as a lower direction. A distance in theupper direction can be defined also as a height when the surface 202 ismade a reference.

The photoelectric conversion unit 218 includes an electrode 219, aphotoelectric conversion layer 220, and an electrode 221, and has alight incident surface. The electrode 219 (a first electrode) isreferred also to as a lower electrode, composed of an electric conductormade mainly from, for example, aluminum or copper. The electrode 219 hasa lower surface 219 a and an upper surface 219 b. The electrode 221 (asecond electrode) is referred also to as an upper electrode, which islocated further toward the light incident surface than the electrode219. The electrode 221 is desirably made from a transparent conductivematerial, e.g., an electric conductor composed mainly of, for example,indium tin oxide (ITO) or polyimide. The electrode 221 includes a lowersurface 221 a and an upper surface 221 b. The electrode 221 iselectrically connected to a wiring layer 210 via an electric conductor224. The electric conductor 224 is made, for example, of the samematerial as that of the electrode 221. The photoelectric conversionlayer 220 is made from a photoelectrically convertible materialconsisting of an inorganic material or an organic material. An inorganicmaterial layer selected from, for example, an amorphous silicon layer,an amorphous selenium layer, a quantum dot layer, and a compoundsemiconductor layer may be used as the photoelectric conversion layer220. An organic material selected from a dye, such as a metal complexdye and a cyanine dye may be used as the material for the photoelectricconversion layer 220. In addition, derivatives, such as acridine,coumarin, triphenylmethane, fullerene, aluminum quinoline,polyparaphenylene vinylene, polyfluorene, polyvinyl carbazole,polythiol, polypyrrole, and polythiophene may be used as the materialfor the photoelectric conversion layer 220. A quantum dot layer may beused as the photoelectric conversion layer 220. The quantum dot layer iscomposed, for example, of a buffer material of AlGaAs or GaAs andquantum dots of InAs or InGaAs. Here, the light incident surface of thephotoelectric conversion unit 218 is, for example, the upper surface 221b of the electrode 221.

The photoelectric conversion apparatus includes a member 225 thatconstitutes a light guide together with the photoelectric conversionlayer 220. The member 225 may be made from any material having arefractive index lower than that of the photoelectric conversion layer220, and is made from silicon oxide in the present embodiment.

A shape of the light guide of the present embodiment is described. Thelight guide is provided at least between a surface including the uppersurface 219 b of the electrode 219 and a surface including the lowersurface 221 a of the electrode 221. The light guide guides light usingreflection or refraction on an interface between the side surfaces 220 cand 220 d of the photoelectric conversion layer 220 and the member 225.In the present embodiment, the member 225 has an opening, in which thephotoelectric conversion layer 220 is provided. The photoelectricconversion layer 220 includes a portion 226 surrounded by the member225. The light incident surface of the photoelectric conversion unit 218is the upper surface 221 b of the electrode 221. An area of a surface (afirst surface) of the portion 226 parallel to the light incident surfaceis smaller than an area of a surface (a second surface) of the portion226 parallel to the light incident surface and disposed between thefirst surface and the electrode 221. An area of orthogonal projection tothe light incident surface of the electrode 219 is smaller than an areaof orthogonal projection to the light incident surface of the secondsurface. That is, the aperture ratio is maintainable because the area ofthe photoelectric conversion layer 220 on the side of the lightincidence is larger than the area of the photoelectric conversion layer220 on the side of the electrode 219. Since the parasitic capacitanceproduced in a node of the electrode 219 can be reduced because of thearea of the electrode 219 being small, the noise (kTC noise) can bereduced. Therefore, it is possible to reduce the noise while maintainingthe aperture ratio. Here, the kTC noise is obtained by Q=(kTC)^(0.5)when the charge number that becomes noise is denoted by Q (k: constant,T: temperature, C: capacitance of photoelectric conversion layer).

In the present embodiment, an area of a set first surface corresponds,for example, to an area of the lower surface 220 a of the portion 226,and an area of a set second surface corresponds, for example, to an areaof the upper surface 220 b of the portion 226. Here, the area oforthogonal projection to the light incident surface of the electrode 219coincides with the area of the lower surface 219 a. As illustrated inFIG. 2, the upper surface 220 b has a width of a length d23, the lowersurface 220 a has a width of a length d24, and the lower surface 219 ahas a width of a length d25. The relationship among these lengths islength d23>length d24 and length d23>length d25. Here, the widthcorresponds to, for example, the length of the member or the openingalong the direction horizontal to the surface 202 of the substrate 201.In subsequent description, when describing the width, each configurationhas the same planar structure as that illustrated in FIG. 7A. Here, thewidth of the area of each surface of the member and the width of theelectrode are the maximum length.

The relationship among the surfaces seen in plan view is illustrated inFIG. 7A. FIG. 7A is a schematic diagram in which outer edges ofarbitrary structures are projected to the light incident surface. Aprojection image of each configuration is referred also to as orthogonalprojection. The upper surface 220 b has the largest outer edge, and thelower surface 220 a and the lower surface 219 a are located inside theouter edge of the upper surface 220 b. In the present embodiment, thelower surface 220 a and the lower surface 219 a have the same area, andthe upper surface 219 b of the electrode 219 also has the same area.Areas of the lower surface 220 a of the photoelectric conversion layer220, the upper surface 219 b of the electrode 219, and the lower surface219 a of the electrode 219 may be different from each other, but it isdesirable that the area of the lower surface 220 a is equal to orsmaller than the area of the upper surface 219 b of the electrode 219.That is, as illustrated in FIG. 7B, it is desirable that an outer edgeof the lower surface 220 a is located inside the outer edge of the uppersurface 219 a of the electrode 219. With this configuration, signalsgenerated in the photoelectric conversion layer can be electricallycollected efficiently. If the area of the lower surface 220 a is smallerthan the area of the upper surface 219 b of the electrode 219, theelectrode 219 can function as an etching stop during the formation ofthe opening and, therefore, a photoelectric conversion apparatus withless damage can be provided.

Hereinafter, other configurations illustrated in FIG. 2 are describedbriefly. A plurality of transistors 216 are arranged on the substrate201 in the region 101. A plurality of transistors 217 are arranged onthe substrate 201 in the region 102. The plurality of transistors 217constitute the above-described readout circuit and peripheral circuits.A wiring structure 203 is provided on the surface 202 of the substrate201. The wiring structure 203 includes insulating layers 204 to 206provided across the regions 101 and 102, and insulating layers 207 and208 provided in the region 102. The wiring structure 203 includes wiringlayers 209 and 210 provided in both the regions 101 and 102, and wiringlayers 211, 212, and 213 provided in the region 102 and not provided inthe region 101. The wiring layers are located in mutually differentheights, and have various circuit patterns. The wiring layer 212functions as a light-shielding film for reducing light incident on thesubstrate 201 in, for example, at least a part of the region 102. Thewiring layer 213 functions as a terminal (a pad portion) for connectionwith the outside. The protective layer 214 covers the wiring layer 213from above the photoelectric conversion unit 218 in the region 101, andincludes an opening 215 through which a part of the upper surface of thewiring layer 213 is exposed. A color filter layer 222 and a microlenslayer 223 are provided on the protective layer 214 in the region 101.The color filter layer 222 includes a plurality of color filters, andthe microlens layer 223 includes a plurality of microlenses.

In the present embodiment, the photoelectric conversion layer 220includes an upper surface 220 e, and is provided between an uppersurface 225 b of the member 225 and the lower surface 221 a of theelectrode 221 in contact with the upper surface 225 b and the lowersurface 221 a. That is, the photoelectric conversion layer 220 isT-shaped as illustrated in FIG. 2. In this case also, the light guide isconstituted by the portion 226 of the photoelectric conversion layer220, and the height of the light guide can be expressed by, for example,(length d21)−(length d22). Here, the height corresponds to the length(the maximum length) of, for example, a member or an opening providedalong a direction vertical to the surface 202 of the substrate 201. Thephotoelectric conversion layer 220 does not necessarily have to have theT-shape, and the upper surface 220 b of the portion 226 may exist on thesame plane as that of the upper surface 225 b of the member 225. Thatis, the electrode 221 may be provided in contact with the upper surface225 b of the member 225 and the upper surface 220 b of the portion 226,and the lower surface 221 a of the electrode 221 may be flat. A portionbetween the upper surface 220 b of the portion 226 of the photoelectricconversion layer 220 and the upper surface 220 e may be constituted by afilm made of another material.

The light guide is tapered in the present embodiment, but the shape ofthe light guide is not limited to the same. The first surface and thesecond surface are described using the areas of the lower surface andthe upper surface of the light guide in the present embodiment, but thefirst surface and the second surface are not limited to the uppersurface and the lower surface of the light guide. In the presentembodiment, the transfer transistor is exemplified as the transistor ofthe readout circuit, and the electrode 219 of the photoelectricconversion unit 218 is connected to a source of the transfer transistor.A drain of the transfer transistor may be connected to a signal line oran amplifier circuit. However, these configurations are not restrictive.The portion to which the electrode 219 of the photoelectric conversionunit 218 is connected may, for example, be connected to a gate electrodeof the amplifying transistor that constitutes a source follower circuit.

In the present embodiment, the upper surface 221 b of the electrode 221is used as the light incident surface. However, if the upper surface 221b is an unsmooth surface, a surface including an arbitrary point on theupper surface 221 b and vertical to the light incident vertically on thephotoelectric conversion apparatus is used as the light incidentsurface.

Second Embodiment

A second embodiment is described with reference to FIG. 3. The secondembodiment differs from the first embodiment in the width of the lightguide. In the present embodiment, the same configurations as those ofthe first embodiment are denoted by the same reference numerals anddescription thereof is omitted. In the present embodiment,configurations corresponding to those of the first embodiment aredenoted by the reference numerals with the same last two digits as thosein the first embodiment and detailed description thereof is omitted.

A photoelectric conversion unit 318 of the present embodiment includesan electrode 219, a photoelectric conversion layer 320 provided on theelectrode 219, and an electrode 221 provided on the photoelectricconversion layer 320. The photoelectric conversion apparatus of thepresent embodiment includes an opening through which a part of an uppersurface of the electrode 219 is exposed, and includes a member 325 thatconstitutes a light guide together with a portion 326 of thephotoelectric conversion layer 320 provided in the opening. The width ofthe portion 326 of a set first surface has the length d32, the width ofthe portion 326 of a set second surface has the length d31, and thewidth of the electrode 219 is the length d33. These lengths satisfy therelationship of length d31>length d32 and length d31>length d33. Also inanother portion 326, the width of a set first surface has the lengthd35, the width of a set second surface has the length d34, and the widthof the electrode 219 is the length d36. These lengths satisfy therelationship of length d34>length d35 and length d34>length d36.

In the present embodiment, a color filter layer 322 includes a firstcolor filter 322 a corresponding to a first color, and a second colorfilter 322 b corresponding to a second color different from the firstcolor. Here, the first color filter 322 a and the second color filter322 b have mutually different spectral transmittance profiles. In thisconfiguration, the photoelectric conversion unit 318 corresponding tothe first color filter 322 a has the length d31 as the width of theopening on the upper surface 325 b of the member 325. The photoelectricconversion unit 318 corresponding to the second color filter 322 b hasthe length d34 as the width of the opening in the height of the uppersurface 325 b of the member 325. Here, the length d31 differs from thelength d34 and is, for example, length d31>length d34.

The relationship between these widths is described. For example, if itis desirable to obtain uniform sensitivity when white light is incidenton the color filter layer 322 for visible light, the following settingis made. If the amount of light passing through the first color filter322 a is smaller than the amount of light passing through the secondcolor filter 322 b, the length d31 is set to be greater than the lengthd34. Variation in the amount of charge produced in the photoelectricconversion layer 320 can be reduced by changing the width in accordancewith the spectral characteristics of the color filter. For example, ifit is desirable to reduce color mixing due to diffraction of light onthe color filter layer 322 for visible light, the following setting ismade. If the wavelength of light passing through the second color filter322 b is longer than the wavelength of light passing through the firstcolor filter 322 a, the length d31 is set to be longer than the lengthd34. Color mixing can be reduced by changing the width in accordancewith the spectral characteristics of the color filter. Thus, it ispossible to change the width of the opening in accordance with thecharacteristics of the color filter layer 322.

Here, the width of the opening is the width of the light guide, and is adistance between two side surfaces 320 c and 320 d of the photoelectricconversion layer 320 on a cross section vertical to the surface 202. Thewidth of the opening seen in plan view may be made a reference. Here,the width on the surface including the upper surface 325 b of the member325 is made a reference, but the width of the portion 326 at otherpositions may be made a reference. In the present embodiment, the size(width) of the electrode 219 is also changed when the width of theopening is changed, but the size does not necessarily have to bechanged.

Third Embodiment

A third embodiment is described with reference to FIG. 4. The thirdembodiment differs from the first embodiment in the height of the lightguide and differs from the second embodiment in the height, not width,of the light guide. In the present embodiment, the same configurationsas those of the other embodiments are denoted by the same referencenumerals and description thereof is omitted. In the present embodiment,configurations corresponding to those of the first embodiment aredenoted by the reference numerals with the same last two digits as thosein the first embodiment and detailed description thereof is omitted.

A photoelectric conversion unit 418 of the present embodiment includesan electrode 419, a photoelectric conversion layer 420 provided on theelectrode 419, and an electrode 221 provided on the photoelectricconversion layer 420. The photoelectric conversion apparatus includes amember 425 having an opening through which a part of the upper surfaceof the electrode 419 is exposed. The member 425 and the photoelectricconversion layer 420 may function as a light guide as in the firstembodiment. Here, a color filter layer 422 includes a first color filter422 a corresponding to a first color, and a second color filter 422 bcorresponding to a second color different from the first color. Here,the first color filter 422 a and the second color filter 422 b havemutually different spectral transmittance profiles.

In this configuration, a member 426 is provided below the electrode ofthe photoelectric conversion unit 418 corresponding to the first colorfilter 422 a. The member 426 is made, for example, from the samematerial as that of the member 425. The photoelectric conversion layer420 corresponding to the first color filter 422 a has a thicknesscorresponding to the length d41 from the upper surface 419 b of theelectrode 419 to the height of the upper surface 425 b of the member425. The photoelectric conversion unit 418 corresponding to the secondcolor filter 422 b is not provided on the member 426. The photoelectricconversion layer 420 corresponding to the second color filter 422 b hasa thickness corresponding to the length d42 from the upper surface 419 bof the electrode 419 to the height of the upper surface 425 b of themember 425. The length d42 is longer than the length d41. Thus, it ispossible to change the height of the light guide in accordance with thecharacteristics of the color filter layer 422.

The relationship of the height of the light guide is described. Forexample, it is desirable to change the depth in accordance with eachcolor filter included in the color filter layer 422, and absorption oflight in the photoelectric conversion layer 420. For example, if thesecond color filter 422 b is provided to transmit light with a longerwavelength than light that the first color filter 422 a transmits, andif the photoelectric conversion layer 420 is, for example, an amorphoussilicon layer, the length d42 is desirably set to be longer than thelength d41. Thus, it is possible to change the height of the light guidein accordance with the characteristics of the color filter layer 422.

In the present embodiment, the member 426 is formed, the electrode 419is formed, and then the member 425 may be formed. The present embodimentand the second embodiment may be combined.

Fourth Embodiment

A fourth embodiment is described with reference to FIGS. 5A and 5B. Thefourth embodiment differs from the other embodiments in the thickness ofthe photoelectric conversion layer. In the present embodiment, the sameconfigurations as those of the other embodiments are denoted by the samereference numerals and description thereof is omitted. In the presentembodiment, configurations corresponding to those of the firstembodiment are denoted by the reference numerals with the same last twodigits as those in the first embodiment and detailed description thereofis omitted.

FIG. 5A corresponds in particular to the second embodiment, in which awidth of a light guide differs in accordance with the color of a colorfilter of a color filter layer 322. In FIG. 5A, a photoelectricconversion unit 518 includes an electrode 219, a photoelectricconversion layer 520, and an electrode 521. Here, a photoelectricconversion layer 520 covers a side surface of an opening of a member 325from an upper surface 325 b of the member 325, and covers the electrode219. The photoelectric conversion layer 520 is a conformal film havingan upper surface conforming to the shape of the member 325. Similarly,the electrode 521 is also formed as a conformal film having an uppersurface conforming to the shape of an upper surface of the photoelectricconversion layer 520. A protective layer 514 functions as a planarizingfilm in the region 101 filling a recess on the upper surface of theelectrode 521 along the upper surface of the electrode 521.

Also in this configuration, the width of a set first surface of aportion 526 corresponding to a first color filter 322 a has the lengthd52, the width of a set second surface of the portion 526 has the lengthd51, and the width of the electrode 219 is the length d53. These lengthssatisfy the relationship of length d51>length d52 and length d51>lengthd53. Also in a portion 526 corresponding to the second color filter 322b, the width of a set first surface of the portion 526 has the lengthd55, and the width of a set second surface of the portion 526 has thelength d54, and the width of the electrode 219 is the length d56. Theselengths satisfy the relationship of length d54>length d55 and lengthd54>length d56.

FIG. 5B corresponds in particular to the third embodiment, in which aheight of a light guide differs in accordance with the color of a colorfilter of a color filter layer 422. A photoelectric conversion unit 1518includes an electrode 419, a photoelectric conversion layer 1520, and anelectrode 1521. Here, the photoelectric conversion layer 1520 covers aside surface of an opening of a member 425 from an upper surface 425 bof the member 425, and covers the electrode 419. The photoelectricconversion layer 1520 is a conformal film having an upper surfaceconforming to the shape of the member 426. Similarly, the electrode 1521is also formed as a conformal film having an upper surface conforming tothe shape of an upper surface of the photoelectric conversion layer1520. A protective layer 1514 functions as a planarizing film in theregion 101 filling a recess on the upper surface of the electrode 1521along the upper surface of the electrode 1521.

Also in this configuration, the height of the light guide correspondingto the color filter 422 a has the length d57, the height of the lightguide corresponding to the color filter 422 b has the length d58, andthe relationship in lengths is length d57<length d58.

As described above, the photoelectric conversion layer may be thin andconstituted by a conformal film. Since the photoelectric conversionlayer is thinner than the photoelectric conversion layers of the secondand the third embodiments, the shapes of the openings of the member 325and the member 425 are desirably round, elliptical, or rectangular withrounded corners when seen in plan view.

Fifth Embodiment

A fifth embodiment is described with reference to FIG. 6. In the presentembodiment, the same configurations as those of the other embodimentsare denoted by the same reference numerals and description thereof isomitted. In the present embodiment, configurations corresponding tothose of the first embodiment are denoted by the reference numerals withthe same last two digits as those in the first embodiment and detaileddescription thereof is omitted.

In FIG. 6, a photoelectric conversion unit 618 includes an electrode619, a photoelectric conversion layer 620 provided on the electrode 619,an electrode 621 provided on the photoelectric conversion layer 620, anda member 604. Here, a lower surface 619 a of the electrode 619 isprovided in direct contact with a surface 202 of a substrate 201, and iselectrically connected to a semiconductor region 601. The member 604 isprovided on the surface 202 to extend over a region 101 and a region102. The photoelectric conversion layer 620 fills an opening provided inthe member 604, is electrically connected to the electrode 619, andcovers the member 604 in the region 101 other than the opening. Theelectrode 621 covers the photoelectric conversion layer 620, and iselectrically connected to a wiring layer 609 provided in the region 102.A protective layer 214 is provided to extend from the region 101 to theregion 102 over the electrode 621 and the wiring layer 609. Theprotective layer 214 has an opening 215 through which a part of an uppersurface 609 b of the wiring layer 609 is exposed, and the wiring layer609 functions as a terminal. Here, the member 604 and the photoelectricconversion layer 620 constitute a light guide as in the firstembodiment.

Also in this configuration, when seen in cross sectional view, an uppersurface 620 b of the portion 626 has the width of the length d61, acertain surface between the upper surface 620 b and the electrode 619has the width of the length d62, and the length of the lower surface 619a having the maximum width of the electrode 619 has the length d63.Relationships between these lengths are length d61>length d62 and lengthd61>length d63. That is, in the portion 626, an area of a set firstsurface parallel to the light incident surface is smaller than an areaof a set second surface parallel to the light incident surface andlocated between the first surface and the electrode 621. An area oforthogonal projection to the light incident surface of the electrode 619is smaller than an area of orthogonal projection to the light incidentsurface of the second surface.

Hereinafter, as an application of the photoelectric conversion apparatusaccording to each of the embodiments, an image pickup system isdescribed in which the photoelectric conversion apparatus isincorporated. The concept of the image pickup system includes not onlyapparatuses mainly made for photographing, such as a camera, butapparatuses provided with a photographing function as an auxiliaryfunction (e.g., a personal computer and a portable terminal). The imagepickup system includes the photoelectric conversion apparatus accordingto the present invention as illustrated in each embodiment above, and asignal processing unit that processes signals output from thephotoelectric conversion apparatus. The signal processing unit mayinclude, for example, an A/D converter, and a processor that processesdigital data output from the A/D converter.

Each embodiment is illustrative only and not restrictive. For example,the semiconductor substrate is exemplified as the substrate in eachembodiment, but the substrate may be other substrates, such as a glasssubstrate and a flexible board, on which a circuit is formed. Afunctional layer, such as a charge blocking layer, for suppressingcharge entering the photoelectric conversion layer from the electrodemay be provided between at least one electrode and the photoelectricconversion layer. Alternatively, an insulating layer may be providedbetween at least one electrode and the photoelectric conversion layer(this configuration is referred to as an MIS structure). Thephotoelectric conversion layer extends over the upper surface of themember in the embodiments. But the photoelectric conversion layer mayextend only inside the opening, i.e., the photoelectric conversion layermay have an upper surface flush with the upper surface of the member. Asingle or a plurality of insulating layers or protective layers may beprovided. If a plurality of insulating layers or protective layers areprovided, these layers may include different materials. Each embodimentmay be changed or combined suitably. Each embodiment may be manufacturedby publicly known semiconductor manufacturing technology.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A photoelectric conversion apparatus comprising:a substrate; a first electrode disposed on the substrate, a plurality ofpixel electrodes each disposed between the first electrode and thesubstrate, including a first pixel electrode and a second pixelelectrode, a photoelectric conversion layer disposed between the firstelectrode and the plurality of pixel electrodes, and continuouslyextending from a position between the first electrode and the firstpixel electrode to a position between the first electrode and the secondpixel electrode, a member that is in contact with the photoelectricconversion layer, wherein in a cross section of the photoelectricconversion layer, a portion of the photoelectric conversion layer whichis disposed on the first pixel electrode is arranged between a firstportion of the member and a second portion of the member, in the crosssection, a first distance between the first portion and the secondportion of the member at a first level is larger than a second distancebetween the first portion and the second portion of the member at asecond level which is closer to the substrate than the first level is,and the second portion of the member is disposed between the first pixelelectrode and the second pixel electrode and/or on a region between thefirst pixel electrode and the second pixel electrode.
 2. Thephotoelectric conversion apparatus according to claim 1, wherein in thecross section, a width of the first pixel electrode is smaller than thefirst distance.
 3. The photoelectric conversion apparatus according toclaim 2, wherein in the cross section, the width of the first pixelelectrode is larger than the second distance.
 4. The photoelectricconversion apparatus according to claim 1, further comprising: aplurality of lenses including a first lens disposed on the first pixelelectrode and a second lens disposed on the second pixel electrode. 5.The photoelectric conversion apparatus according to claim 4, wherein inthe cross section, a width of the first lens is larger than a width ofthe first pixel electrode.
 6. The photoelectric conversion apparatusaccording to claim 5, wherein the first lens and the second lens are incontact with each other.
 7. The photoelectric conversion apparatusaccording to claim 6, wherein in the cross section, the width of thefirst pixel electrode is smaller than the first distance.
 8. Thephotoelectric conversion apparatus according to claim 7, wherein in thecross section, the width of the first pixel electrode is larger than thesecond distance.
 9. The photoelectric conversion apparatus according toclaim 8, further comprising: a color filter disposed between theplurality of lenses and the first electrode.
 10. The photoelectricconversion apparatus according to claim 1, wherein each of the firstportion of the member and the second portion of the member is tapered.11. The photoelectric conversion apparatus according to claim 1, whereinthe member includes a third portion, in the cross section, a differentportion of the photoelectric conversion layer which is disposed on thesecond pixel electrode is arranged between the second portion of themember and the third portion of the member, in the cross section, athird distance between the second portion and the third portion of themember at the first level is larger than a fourth distance between thesecond portion and the third portion of the member at the second level.12. The photoelectric conversion apparatus according to claim 1, whereinthe photoelectric conversion layer is a quantum dot layer.
 13. Thephotoelectric conversion apparatus according to claim 1, furthercomprising: an insulating layer between the plurality of pixelelectrodes and the photoelectric conversion layer.
 14. The photoelectricconversion apparatus according to claim 1, wherein the photoelectricconversion layer and the member constitute a light guide.
 15. Thephotoelectric conversion apparatus according to claim 1, furthercomprising: a plurality of transistors provided in the substrate andrespectively connected to the plurality of pixel electrodes.
 16. Thephotoelectric conversion apparatus according to claim 1, furthercomprising: a pad electrode, wherein the substrate includes a pixelregion and a peripheral region, the first electrode extends over thepixel region and is connected to the pad electrode provided on theperipheral region.
 17. The photoelectric conversion apparatus accordingto claim 16, further comprising: a wiring layer disposed between theplurality of pixel electrodes and the substrate; and a plurality oftransistors provided in the substrate and respectively connected to theplurality of pixel electrodes via the wiring layer, wherein the wiringlayer connects the first electrode and the pad electrode.
 18. Thephotoelectric conversion apparatus according to claim 17, furthercomprising: a plurality of lenses including a first lens disposed on thefirst pixel electrode and a second lens disposed on the second pixelelectrode.
 19. The photoelectric conversion apparatus according to claim18, wherein in the cross section, a width of the first lens is largerthan a width of the first pixel electrode.
 20. An image pickup system,comprising: the photoelectric conversion apparatus according to claim 1;and a signal processing unit configured to process signals from thephotoelectric conversion apparatus.